Java：为什么“\\\￿”在UTF-8中转换为[-17，-65，-65]？ [英] Java: why "\uFFFF" converts to [-17, -65, -65] in UTF-8?

问题描述

为什么\\\￿（显然为2个字节长）转换为UTF-8中的[-17，-65，-65] -1，-1]？

  System.out.println（Arrays.toString（\\\￿.getBytes（StandardCharsets .UTF_8）））;这是因为对于大于127的码点，UTF-8在每个字节中只使用6位？ 
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解决方案
  0xFFFF 有一个位模式 11111111 11111111 。根据UTF-8规则划分位，模式变为 1111 111111 111111 。现在添加UTF-8的前缀位，并且模式变为 0xEF 0xBF 0xBF 。 * 1110 * 1111 * 10 * 111111 * 10 * 111111  code>，aka  239 191 191 ，aka  -17 -65 -65 是Java用于有符号值的值 -  Java没有无符号数据类型）。
 
Why does "\uFFFF" (which is apparently 2 bytes long) convert to [-17,-65,-65] in UTF-8 and not [-1,-1]?
System.out.println(Arrays.toString("\uFFFF".getBytes(StandardCharsets.UTF_8)));
Is this because UTF-8 uses only 6 bits in every byte for codepoints larger than 127?
解决方案
0xFFFF has a bit pattern of 11111111 11111111.  Divide up the bits according to UTF-8 rules and the pattern becomes 1111 111111 111111.  Now add UTF-8's prefix bits and the pattern becomes *1110*1111 *10*111111 *10*111111, which is 0xEF 0xBF 0xBF, aka 239 191 191, aka -17 -65 -65 in twos complement format (which is what Java uses for signed values - Java does not have unsigned data types).

                        
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